This invention relates to novel pharmaceutical preparations containing coumarin carboxylic acid derivatives which are useful in the treatment of certain chronic complications arising from diabetes mellitus, such as diabetic cataracts and neuropathy.
Although many oral antidiabetic agents, such as the sulfonyl ureas, effectively lower blood sugar levels, the prevention or alleviation of the chronic complications of diabetes, such as diabetic cataracts, neuropathy, retinopathy and nephropathy has proved harder to achieve. According to the U.S. Pat. No. 3,821,383, aldose reductase inhibitors such as 1,3-dioxo-1H-benz[d,e]-isoquinoline-2(3H)-acetic acid and its derivatives are useful in this regard. Spiro-hydantoin or imidazolidinedione compounds are also aldose reductase inhibitors and are described in U.S. Pat. No. 4,117,230, U.S. Pat. No. 4,130,714 and U.S. Pat. No. 4,127,665. Such compounds inhibit the enzymatic reduction of aldoses, such as glucose and galactose, to the corresponding polyols, such as sorbitol and galactitol, thus preventing or reducing the harmful and unwanted accumulations of polyols in the diseased organs of the body; for example, inhibition of glucose reduction would prevent sorbitol accumulation in the lens and retina of the diabetically cataractous eye, in the diabetically neuropathic peripheral nerve and in the diabetically nephropathic kidney.